How effective is intermittent pneumatic compression for the prevention of venous thromboembolism in hospitalized patients?
Intermittent pneumatic compression (IPC) is more effective than doing nothing or using thromboembolic deterrent stockings (TEDS), and is similarly effective to medical thromboprophylaxis for the prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE). It is also safer than anticoagulants. The authors pool the studies to determine absolute risk reductions and numbers needed to treat but this is inappropriate when the baseline risk of DVT, PE, and bleeding varies so much between studies. Using a more statistically correct approach of applying the relative risk from the meta-analysis to the baseline risk of events, I found a number needed to treat to prevent one bleed of 40 for IPC compared with medical thromboprophylaxis, and a number needed to treat of 22 to prevent one DVT by using IPC instead of TEDS. (LOE = 1a)
The authors performed a careful search for randomized trials comparing IPC with either no treatment, TEDS, or pharmacotherapy in hospitalized patients to prevent DVT or PE. They also looked for studies comparing IPC plus pharmacotherapy with IPC alone. The search included PubMed, Embase (a European database), and the Cochrane Controlled Trials Register. Overall, the authors found 70 trials with a total of 16,164 patients, mostly in surgical and postoperative populations. Most trials included patients undergoing orthopedic surgery, major abdominal surgery, urologic surgery, or neurosurgery. The overall quality of studies was fair, with approximately half failing to adequately report allocation concealment or blindly assess outcomes. IPC was more effective than doing nothing in preventing PE (relative risk [RR] = 0.48; 95% CI, 0.33 – 0.69) and DVT (RR = 0.43; 0.36 – 52). IPC was also more effective than TEDS at preventing DVT (95% CI = 0.61; 0.39 – 0.93) but not PE (RR = 0.64; 0.21 – 1.95). Not surprisingly, when compared with medical thromboprophylaxis (usually with unfractionated or low-molecular-weight heparin), patients randomized to receive IPC had less systemic bleeding or bleeding complications (RR = 0.41; 0.25 – 0.65). The overall likelihood of DVT and PE was similar between patients given IPC or medical thromboprophylaxis,but there was considerable heterogeneity of results for the studies of DVT. There was no significant difference in mortality when medical thromboprophylaxis was added to IPC or when medical thromboprophylaxis was compared with IPC. Finally, adding medical thromboprophylaxis to IPC further reduced the risk of DVT but did not significantly reduce the likelihood of PE. As for TEDS, the relative risk was similar for prevention of DVT and PE, but because PE is much less common, the sample size may have been insufficient to demonstrate a significant reduction even if one actually existed.